Hi Folks,

Thanks to all for comments and suggestions, I'm still trying various ways to come up with one solution for all.

Russ, you make good points with your Direction without Wind speed comments. I also have a long history of Oceanographic and Meteorological experience - but as a hardware guy. My venture into writing code has only been recent by comparison so I have the problem of putting the hardware experience into the Black Art... For the record, Tracey ("Boys from Berkeley") Allen's website has been a mine of useful information for me particularly with the math side of things and would encourage anyone regardless of their qualifications to spend some time reading some of his writings.

What I didn't mention in my opening question was that I am also measuring Wind Gust, which by definition, is the highest successive wind speed in a 3 second window - hence my need to also measure the direction over 3 seconds (my opening question). You can read between the lines here to see I am also deriving Highest wind speed, Average wind speed, Wind Gust direction, Average direction and Direction deviation (Sigma Theta) - so I have a number of things to juggle and think about, all within a continuously sliding 3 second window which is moving every 1 second.

I'm making progress but it isn't pretty code! If anyone has some more to input it will be warmly welcomed otherwise I'll keep banging away to streamline things.

Kind regards to all,
Bill